On 29 November 1944, two US Douglas A-26 Invader bomber planes crashed into Warton Marsh, eight miles from Preston, in Lancashire. Both planes, along with a number of others, had left Warton Airbase in formation, en route to join forces in the preparations for the Battle of the Bulge. Only one minute off the runway and 1,000 feet into the air, the aircraft collided and came to rest in the marsh. All the crew died. Their bodies were recovered from the planes, but an investigation into the causes of the crash was inconclusive.When the planes crashed back in 1944, they landed directly on sand. Since then, however, about two metres of silt has built up over the wrecks. It means that the site is a difficult one to excavate, and an earlier attempt to retrieve the aircraft in the 1980s was unsuccessful.For this programme, Time Team enlisted a veteran air crash investigator, along with the RAF's 'crash and smash' team and other experts to try to find out what caused the crash. Each of the planes, including the engines, was believed to be relatively intact and, it was hoped, would provide the necessary information to determine why these two planes collided.Local eyewitnesses and fellow flyers in the US Air Force were all called upon to help to build up a picture of what happened on that fateful day in 1944.